The 20-page document claims the civil rights leader used his organisation as a "tax dodge".

The National Archives recently released a large portion of the files relating to former US President John F Kennedy, relating to his time in office and events that led up to his assassination in November 1963. The latest batch of documents also features a secret FBI dossier on Martin Luther King Jr, which sheds a very negative light on the civil rights activist.

The 20-page analysis dated 12 March, 1968, features information regarding King's history, influences and alleged extra-marital affairs. Titled "Martin Luther King, Jr. A Current Analysis", the report claims "to give some insight into the nature of the man himself as well as the nature of his views, goals, objectives, tactics and the reasons therefor".

In one particular portion of the analysis regarding his personal life, the civil rights icon is described as engaging in "unnatural" and "abnormal" sexual acts.

Referring to a 1968 Miami workshop King held in order to train black ministers in leadership, the author claims the event doubled as a sex orgy of sorts.

"Several Negro and white prostitutes were brought in from the Miami area. An all night-sex orgy was held with these prostitutes and some of the delegates in attendance," the document states.

"One room had a large table in it which was filled with whiskey. The two Negro prostitutes were paid $50.00 to put on a sex show for the entertainment of the guests. A variety of sex acts deviating from the normal were observed."

Other references to orgies come up in the report, as well as King's extra-marital affairs with numerous other women, one of which allegedly led to the birth of a baby girl.

"It was learned in February, 1968, from a very responsible Los Angeles individual in a position to know, that King has been having an illicit love affair with the wife of a prominent Negro dentist in Los Angeles, California, since 1962. He believes King fathered a baby girl born to this woman inasmuch as her husband is allegedly sterile," the analysis reads.

Another section of the documents refer to the Southern Christian Leadership Conference, the African-American civil rights organisation founded by King. The FBI describes it as "a tax dodge" while alleging ties between the Baptist minister and communist influences.

The information revealed in the files released on 3 November has been received with a certain level of scepticism for numerous reasons. There are no details of how and if the information was properly verified and it is not clear why they were part of the JFK files considering they make no mention of the president.

"When we look closely at this, what we see is that there is a person who is trying his best to damage Martin Luther King's reputation," Clayborne Carson, the director of the Martin Luther King, Jr Research and Education Institute told CNN, hinting at then FBI Director J Edgar Hoover, who was known to be hostile to King.

Coretta Scott King and her husband Martin Luther King in December 1964AFP/Getty Images